Previous studies in this laboratory have shown abnormalities in platelet function in Sickle Cell disease. We intend to continue these studies measuring the nucleotides of the platelets. We have also initiated viscometric studies of the blood of patients with Sickle Cell disease, attempting to use this method to detect the onset of crises, results of therapy, etc. We intend to perform in depth studies of the coagulation mechanism, platelet function, and platelet turnover in patients with rapidly progressing glomerulonephritis. We shall continue the work commenced last year in studying the coagulation mechanism and platelet function as related to diabetic retinopathy where increased aggregability of the platelets has been shown by other authors. We intend to use autologous labelled fibrinogen instead of commercial labelled fibrinogen as a method of studying development and pathology of thrombophlebitis. Bibliographic references: Menafee, M., Flessa, H.C., Glueck, H.I., Hogg, S.: Hereditary Hemorrhagic Telangiectasia (Osler-Weber-Rendu Disease). Archives of Otolaryngology 101:246-251, '75. Settle, Harold and Glue ck, Helen, I.: Disseminated Intravascular Coagulation with Influenza. Ohio State Journal 71:541, '75.